The prior art discloses a proximity fuse which comprises an electronic circuit which is sensitive to signals in given frequency bands. The circuit, which may be an integral part of a projectile, responds to signals transmitted from the designated target, or it responds to reflected signals originally transmitted from the launched projectile, e.g. doppler signals.
Proximity fuses of this type are, however, subject to the risk of being influenced by spurious signals, which may cause false detonation of the projectile.